SharePoint Intranet: Choosing the right WebPart for Intranet Updates! Yammer VS Announcements

I'm setting up our intranet with SharePoint and the management wants me to set up a feed similar to Twitter on our homepage. Here are 2 scenarios I've considered, and I'd love to hear your thoughts:

1) setup an announcement webpart on every team subsites (we have 8 teams), then set up our Intranet homepage so that the announcement webpart of the intranet gets a constant feed from those. I could set up a workflow so that everyone receives a weekly email of the new announcement feed just like twitter does.

2) Maybe encourage teams to go on yammer and use specific hashtags, then setup a content rollup to report on those hashtags, then setup a workflow to email everyone with the latest updates.

Any thoughts as to what would be better? Is there a webpart that I forgot that might offer a better solution?